Tamoxifen-failed male breast cancer with a high level of circulating estrogen: Report of a case

We report herein the case of a 40-year-old man with grade II invasive ductal carcinoma of the breast (pT1, pN0, M0: stage I) in whom a recurrence developed shortly after completion of a 2-year course of tamoxifen and 5-fluorouracil therapy following a mastectomy. Although the metastatic tumor was estrogen receptor-positive, hormone therapy combined with chemotherapy had no significant effect on tumor growth, and the patient died from disseminated tumors 2 years 6 months after completion of the adjuvant therapy. It is noteworthy that the circulating estradiol level increased from 18.0 to 892.3 pg/ml during the period of tumor progression and dissemination. We interpret these findings as an indication of high aromatase activity in the metastatic tumors. We suggest that extending tamoxifen treatment to 5 years or longer be recommended for the standard adjuvant hormone therapy of male breast cancer to prevent the early recurrence of hormone-responsive disease.